1. Field of the Invention
The present invention relates to method and apparatus for testing a vehicle such as an automobile, and for testing a suspension system of the vehicle.
2. Description of Related Art
A vehicular suspension system is an important part which affects riding comfort in a vehicle, and it is essential to make a preliminary evaluation of the performance thereof in developing the vehicle. Thereafter, conventionally, the vehicular suspension system has been tested either by driving an actual car on a road or by using an actuator. The latter is carried out by placing each wheel of an actual car on an exciting unit and exciting the body by an actuator to simulate road conditions. The body is supported by the wheels and the suspension system and the performance of the suspension system is evaluated by measuring the body motion. An example thereof has been described by Miyajima et. al. "Laboratory System Endurance Testing of Automobile Major Components", Mitsubishi Juko Giho, Vol. 19, No. Jan. 1, 1982, pp. 26-34. In this example, a vibration having a waveform such as obtained by an actual vehicle running test is reproduced by an actuator. Further, Japanese Patent Laid-open No. Hei. 7-35654 has disclosed a so-called active suspension testing system in which rollers are driven by an actuator so as to simulate irregularities of a road in a chassis dynamometer for driving an actual car on a bench of the rotating rollers.
However, the actual vehicle running tests described above can be used only under a certain conditions in which several parameters (e.g., structure of body, road surface condition, running condition, etc.) are all predetermined, so that it has been difficult to apply the result of the experiment to the evaluation of other conditions. In addition, recently developed active suspension systems which introduce a feedback signal to a controller of a suspension, enlarge the scale of the test and lack generality because the actual vehicle is used. The same applies also in the case of the exciting test. Since the active suspension system requires information on operating feedback signals, those exciting methods which do not provide such information are unable to deal with such suspension.
Accordingly, it is an object of the present invention to provide a vehicle testing method and apparatus which allow performance or durability testing of the suspension system, including active suspension systems, to be carried out readily under various conditions.